Vehicle control system with advanced tire monitoring

ABSTRACT

A control system ( 11 ) for a vehicle ( 10 ) includes vehicle dynamics sensors ( 35 - 47 ) providing a vehicle dynamics signal. Tire monitoring system sensors ( 20 ) in each wheel generate tire signals including temperature, pressure and acceleration data. A controller ( 26 ) communicates with the tire monitoring system sensors ( 20 ) and at least one vehicle dynamics sensor, and generates a suspension value as a function of the multi-axis acceleration data of the tire signals. The suspension value is transmitted to a suspension control system ( 33 ) to adjust the vehicle suspension characteristics in response to the suspension value.

CROSS REFERENCE

This application is a divisional of U.S. patent application Ser. No.11/693,175 filed on Mar. 29, 2007 now U.S. Pat. No. 8,032,281, titledVehicle Control System With Advanced Tire Monitoring, hereinincorporated by reference.

TECHNICAL FIELD

The present invention relates generally to vehicle control systems andtire monitoring systems. More particularly, the present invention isrelated to vehicle control systems incorporating advanced tiremonitoring for comfort and convenience.

BACKGROUND

Tire pressure monitoring may soon become a standard feature on vehicles.Current tire pressure monitoring sensors, however, have limitedfunctionality, and are not capable of discerning coordinate accelerationdata for a wheel. Conventional tire pressure sensors provide pressureand temperature sensing along with data processing and wirelesscommunication of such data. Most also include a movement detectiondevice such as switch or piezoelectric device that activates upon aradial acceleration. The movement detection devices “wake” the sensor toinitiate data transmission, while saving battery life while the wheel isnot moving.

Advanced tire monitoring sensors (ATMS) are currently being developed.Besides traditional pressure and temperature data, ATMS includecoordinate acceleration data for the associated wheel. This isaccomplished with micro-electro-mechanical system (MEMS) accelerometers.Such devices have advantages in terms of robustness, and the ability toprovide a linear output response to acceleration. Multiple MEMS are alsocontemplated to provide multi-axis (coordinate) acceleration data forthe associated wheel.

ATMS provide the potential to vehicle manufacturers to offer new orenhanced capabilities in vehicle systems. The present disclosure isdirected toward providing improved vehicle comfort and conveniencesystems utilizing ATMS.

SUMMARY OF THE INVENTION

One embodiment of the present invention provides a system for a vehicleincluding a tire sensor located within each wheel of the vehicle andgenerating a tire signal comprising pressure, temperature and multi-axisacceleration data. The system also includes at least one vehicledynamics sensor providing a vehicle dynamics signal, such as the vehiclespeed and braking. Further, a controller communicates with the tiresensor and the at least one vehicle dynamics sensor. The controller, inresponse to the vehicle dynamics signal, generates a roadway surfacecondition estimation value as a function of the multi-axis accelerationdata of the tire signal, and transmits the roadway surface conditionestimation value to at least one vehicle system controller. The systemcontroller can be a suspension control system.

The controller generates the roadway surface condition estimation valueas a function of the tire signal by comparing frequency and amplituderesponse characteristics of the tire signal to stored frequency andamplitude response characteristics indicative of different roadwaysurfaces. An indicator can signal to the vehicle operator the roadwaysurface condition estimation value.

The suspension control system can include any one of an activesuspension component for altering suspension geometry, a pneumaticcylinder adapted to adjust vehicle ride height, an adjustable suspensiondamper, or a central tire inflator adapted to adjust tire inflation.Thus, when the roadway surface condition estimation value indicates arough surface, the suspension control system is adapted to soften thevehicle suspension characteristics. Conversely, when the roadway surfacecondition estimation value indicates a smooth surface, the suspensioncontrol system stiffens the vehicle suspension characteristics.

In another aspect of the invention, the roadway surface conditionestimation value dictates a first suspension value used to adjust thesuspension system accordingly. A user-selected second suspension valuemay also be included. When a user-selected second suspension value ispresent, the suspension control system adjusts the vehicle suspensioncharacteristics as a function of the first and second suspension values.In one example, the suspension control system adjusts the vehiclesuspension characteristics according to the second suspension value whenthe first and second suspension values are compatible, and adjusts thevehicle suspension characteristics according to the first suspensionvalue when the first and second suspension values are incompatible. Inthis way, the user-selected value controls unless the road surfaceconditions indicate that ride and handling can be improved by modifyingthe suspension. This may be done to avoid the suspension components“bottoming out” (contacting hard stops), for example.

In another embodiment, the system mitigates rear wheel hop. The systemincludes a tire sensor located within each wheel of the vehicle andgenerating a tire signal comprising pressure, temperature and multi-axisacceleration data; at least one vehicle dynamics sensor providing avehicle dynamics signal; a brake system for applying a braking torque toeach of the vehicle wheels in response to a brake signal; and acontroller communicating with the tire sensor and the at least onevehicle dynamics sensor. In response to the vehicle dynamics signal,controller generates the brake. signal as a function of the multi-axisacceleration data of the tire signal, and transmits the brake signal tothe brake system. The controller can generate the brake signal bycomparing frequency and amplitude response characteristics of the reartire signals, to frequency and amplitude response characteristics of thefront tire signals to determine a rear wheel hop event. To mitigate therear wheel hop event, braking maneuvers can be performed.

The embodiments of the present invention provide several advantages. Oneadvantage provided by an embodiment of the present invention is asuspension control system that is capable of obtaining tire pressure andwheel acceleration knowledge and adjusting suspension control functionsaccordingly to improve vehicle ride and handling.

The present invention itself, together with further objects andattendant advantages, will be best understood by reference to thefollowing detailed description, taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of this invention reference should nowbe had to the embodiments illustrated in greater detail in theaccompanying figures and described below by way of examples of theinvention wherein:

FIG. 1 is a block diagrammatic and perspective view of a vehicle withvariable vectors and coordinate frames in accordance with an embodimentof the present invention;

FIG. 2 is a block diagrammatic view of a tire monitoring system inaccordance with an embodiment of the present invention;

FIG. 3 is a block diagrammatic view of a tire sensor according to anembodiment of the present vehicle control system;

FIG. 4 is a block diagrammatic view of a control system, including atire monitoring system for a vehicle in accordance with an embodiment ofthe present invention;

FIG. 5 is a logic diagram illustrating a method of operating a controlsystem of a vehicle in accordance with an embodiment of the presentinvention providing road surface characteristic estimation;

FIG. 6 is a graphical representation of ATMS sensor amplitude-timeresponse data;

FIG. 7 is a graphical representation of ATMS sensor magnitude-frequencyresponse data;

FIG. 8 is a logic flow diagram illustrating a method of estimating aroadway surface characteristic in accordance with the method of FIG. 5;

FIG. 9 is a logic diagram illustrating a method of operating a controlsystem of a vehicle in accordance with an embodiment of the presentinvention providing active suspension control; and

FIG. 10 is a logic flow diagram illustrating a method of activesuspension control in accordance with the method of FIG. 9.

DETAILED DESCRIPTION

In the following figures, the same reference numerals will be used toidentify the same components. The present invention may be used inconjunction with vehicle control systems including a yaw stabilitycontrol (YSC) system, roll stability control (RSC) system, lateralstability control (LSC) system, integrated stability control (ISC)system, or a total vehicle control system for achieving desired vehicleperformance. The present invention is also described with respect to anintegrated sensing system (ISS), which uses a centralized motion sensorcluster such as an inertial measurement unit (IMU) and other available,but decentralized, sensors. Although a centralized motion sensor, suchas an IMU, is primarily described, the techniques described herein areeasily transferable to using the other discrete sensors.

In the following description, various operating parameters andcomponents are described for several constructed embodiments. Thesespecific parameters and components are included as examples and are notmeant to be limiting.

Referring to FIG. 1, an automotive vehicle 10 with a control system ofthe present invention is illustrated with the various forces and momentsthereon. Vehicle 10 has front right (FRW) and front left (FLW)wheel/tires 12 a and 12 b and rear right (RRW) wheel/tires 12 c and rearleft (RLW) wheel/tires 12 d, respectively. The vehicle 10 may also havea number of different types of front steering systems 14 a and rearsteering systems 14 b, including having each of the front and rearwheels 12 a, 12 b, 12 c and 12 d configured with a respectivecontrollable actuator, the front and rear wheels 12 having aconventional type system in which both of the front wheels 12 a, 12 bare controlled together and both of the rear wheels 12 c, 12 d arecontrolled together, a system having conventional front steering andindependently controllable rear steering for each of the wheels 12 c and12 d, or vice versa. Generally, the vehicle 10 has a weight representedas Mg at the center of gravity of the vehicle 10, where g=9.8 m/s² and Mis the total mass of the vehicle 10.

The control system 11 has an active/semi-active suspension system, andmay include rollover mitigation and prevention systems, which includeand/or comprise of, an active steering system, a deployable lateralstability system, inwardly mounted wheel assemblies, and other relateddevices such as known in the art. The control system 11 may also be usedwith or include an anti-roll bar, or airbags or other safety devicesdeployed or activated upon sensing predetermined dynamic conditions ofthe vehicle 10.

The control system 11 is in communication with a sensing system 16. Thesensing system 16 may have many different active and passive sensorsincluding the sensor set typically found in a roll stability control ora rollover control system (including lateral accelerometer, yaw ratesensor, steering angle sensor and wheel speed sensor which are equippedfor a traditional yaw stability control system) together with a rollrate sensor and a longitudinal accelerometer. The sensing system 16 mayalso includes object detection sensors, which aid in the detection of animminent rollover obstacle. The various sensors will be furtherdescribed below and are shown with respect to FIGS. 2 and 4.

The sensors may also be used by the control system 11 in variousdeterminations such as to determine a lifting event, determine a heightand position of a mass, etc. Wheel speed sensors can be mounted at eachcorner of the vehicle and generate signals corresponding to therotational speed of each wheel. The rest of the sensors of the sensingsystem 16 may be mounted directly on the center of gravity of thevehicle body, along the directions x, y, and z shown in FIG. 1. As thoseskilled in the art will recognize, the frame from b₁, b₂, and b₃ iscalled a body frame 22, whose origin is located at the center of gravityof the car body, with the b₃ corresponding to the x axis pointingforward, b₂ corresponding to the y axis pointing off the driving side(to the left), and the b₃ corresponding to the z axis pointing upward.The angular rates of the car body are denoted about their respectiveaxes as ω_(x) for the roll rate, ω_(y) for the pitch rate and ω_(z) forthe yaw rate. Calculations may take place in an inertial frame 24 thatmay be derived from the body frame or chassis 22 as described below.

The angular rate sensors and the accelerometers may be mounted on thevehicle car body along the body frame directions b₁, b₂, and b₃ whichare the x-y-z axes of the sprung mass of the vehicle.

The longitudinal acceleration sensor is mounted on the car body locatedat the center of gravity, with its sensing direction along b₁ axis,whose output is denoted as a_(x). The lateral acceleration sensor ismounted on the car body located at the center of gravity, with itssensing direction along b₂ axis, whose output is denoted as a_(y).

FIG. 1 depicts a road frame system r₁r₂r₃ that is fixed on the drivenroad surface, where the r₃ axis is along the average road normaldirection computed from the normal directions of the four-tire/roadcontact patches.

Referring now to FIG. 2, a block diagrammatic view of an advanced tiremonitoring system ATMS (18) for a vehicle 10 in accordance with anembodiment of the present invention is shown. The control system 11includes a controller 25. The controller may be a controller forestimating a roadway surface condition and modifying a suspensioncharacteristic in response to the estimated roadway surface conditions.Examples of such comfort and convenience control systems CCS 25 aredescribed below. The control system 11 utilizes tire status informationgathered from the advanced tire monitoring system ATMS 18 in operationof the controller 25. The ATMS 18 provides tire pressure, tiretemperature and acceleration data to the control system 25. A sampleadvanced tire monitoring system is described in detail with respect toFIGS. 2 and 3. A sample comfort and convenience control system isdescribed with respect to FIG. 4. Logic routines for different comfortand convenience functions are described with respect to FIGS. 5 through10.

The control system 11 includes one or more controllers. The controllersmay be part of the advanced tire monitoring system 18, the conveniencecontrol system 25, or may be a stand-alone controller. The conveniencecontrol system 25 may be coupled to other control systems to respond tosafety, comfort or convenience events as detected by the logic routinesand ATMS 18. Such control systems could include a brake control systemthat is used to actuate brakes; a suspension control system foractivating, suspension components to mitigate the effect of a detectedevent; a steering control system to likewise mitigate a detected event;active and passive safety control systems; a central tire inflationsystem, and the like. Control events related to safety, comfort orconvenience may be indicated to a vehicle occupant via an indicator 90.

Several of the stated control systems are shown and described withrespect to FIG. 4. Therein, the control system 11 is illustrated infurther detail having a controller 26, a passive safety system 27-30,multiple active systems 31-34, various vehicle status sensors and driveror vehicle operator input sensors 20 and 35-47. The passive system 27includes object detection devices or sensors 28, collision detectionsensors 29, and various passive countermeasures 30. The active systemsmay include a brake control system 31, a steering control system 32, asuspension control system 33, and a drivetrain control system 34. Basedupon inputs from the sensors, the convenience control system 25 mayoperate the safety device 51. Further, although it is shown as a safetydevice 51, it also activates the comfort and convenience featuresdiscussed herein, because several of the mechanisms provide dual rolesin improving passenger comfort and mitigating safety-relate events.

The controllers described herein may be microprocessor based such as acomputer having a central processing unit, memory (RAM and/or ROM), andassociated input and output buses. The controllers may beapplication-specific integrated circuits or may be formed of other logicdevices known in the art. The controllers may each be a portion of acentral vehicle main control unit, an interactive vehicle dynamicsmodule, a restraints control module, a main safety controller, a controlcircuit having a power supply, combined into a single integratedcontroller, or may be a stand-alone controller as shown.

Referring again to FIG. 2, the advanced tire monitoring system 18monitors the air pressure, temperature and multi-axis accelerations fora right front tire 12 a, a left front tire 12 b, a right rear tire 12 c,and a left rear tire 12 d. Each tire 12 a-12 d has a respective tireATMS sensor 20 a-20 d, each of which has a respective antenna 19 a-19 d.Each tire 12 a-12 d is positioned upon a corresponding wheel.

A fifth tire or spare tire 12 e is also illustrated having an ATMSsensor 20 e and a respective antenna 19 e. Although five wheels areillustrated, the tire status of various numbers of wheels may bemonitored. For example, the present invention applies equally tovehicles such as pickup trucks that have dual wheels for each rearwheel. Also, various numbers of wheels may be used in a heavy-duty truckapplication having dual wheels at a number of locations. Further, thepresent invention is also applicable to trailers and extra spares.

Each tire 12 may have a respective initiator 23 a-23 e positioned withinthe wheel wells adjacent to the tire 12. Initiator 23 generates a lowfrequency RF signal initiator and is used to initiate a response fromeach wheel so that the position of each wheel may be recognizedautomatically by the advanced tire monitoring system 18. Initiators 23are coupled directly to the advanced tire monitoring system 18. Incommercial embodiments where the position programming is done manually,the initiators may be eliminated.

The controller comprising the ATMS 18 may be microprocessor basedcontroller having a programmable CPU that may be programmed to performvarious functions and processes including those set forth herein.Controller has a memory 18 a associated therewith. Memory 18 a may bevarious types of memory including ROM or RAM. The memory is used tostore various thresholds, calibrations, tire characteristics, wheelcharacteristics, serial numbers, conversion factors, temperature probes,spare tire operating parameters, and other values needed in thecalculation, calibration and operation of the advanced tire monitoringsystem 18. For example, memory may contain a table that includes thesensor identification. Also, the warning status of each of the tires mayalso be stored within the table.

The ATMS 18 is also coupled to a transceiver 80. Although thetransceiver 80 is illustrated as a separate component, the transceiver80 may also be included within ATMS 18. The transceiver 80 has anantenna associated therewith. The antenna is used to receive pressure,temperature and multi-axis acceleration information from tire ATMSsensors 20 a-20 e. One transceiver may be used for all of the tire ATMSsensors 20, or a front and rear transceiver may be used, or dedicatedtransceivers may be used, each in communication with the ATMS 18. TheATMS 18 performs preprocessing before placing the tire data on thevehicle communications bus (CAN) or other digital protocol fortransmission to the convenience control system 25.

In the example shown, the convenience controller 25 is also coupled to aplurality of sensors 81 and other measurement and control systems suchas an IMU 82. The sensors 81 may include a barometric pressure sensor,an ambient temperature sensor, an object detection sensor, a speedsensor, a brake pedal sensor, a throttle position sensor, steering wheelposition sensor, and an ignition sensor. Sensor data may also beprovided such as suspension position and loading. Of course, variousother types of sensors may be used. A barometric pressure sensorgenerates a barometric pressure signal corresponding to the ambientbarometric pressure. Thus, barometric pressure compensation may be used,but is not required in the calculation for determining the pressurewithin each tire 12. The ambient temperature signal corresponding to theambient temperature and may also be used to generate a temperaturecompensated pressure profile. The sensor data 81 may also bepreprocessed before being communicated to the convenience control system25.

The inertial measurement unit (IMU) 82 contains inertial sensors fordetecting vehicle yaw, pitch and roll. This data is communicated to theconvenience control system 25 (when used as part of a safety controlsystem) in order to determine whether a rollover event exists. This datacan also act to initiate the ATMS 18 when a potential for rolloverexists, or indicate that data collection from the ATMS sensors 20 isdesirable.

Safety, comfort and convenience devices are generally indicated at 51.Safety devices may include restraints components such as seat mountedside airbags or side curtain airbags, seat belt pretensioners,deployable trim panels and the like. To prevent or mitigate a rolloverevent, safety devices 51 may also include vehicle lateral supportsystems, wheel sets or active suspension components. Comfort andconvenience devices may include suspension components such as activebushings or linkages and, pneumatic or hydraulic cylinders. They mayalso include a centralize tire inflator for changing the amount of tirepressure at each of the tires 12.

Control system 25 may also be coupled to an indicator 90. The indicator90 may include a video system, an audio indicator, a heads-up display, aflat-panel display, a telematic system, a dashboard indicator, a panelindicator, or other indicator known in the art. In one embodiment of thepresent invention, the indicator 90 is in the form of a heads-up displayand the indication signal is a virtual image projected to appear forwardof the vehicle 10. The indicator 90 provides a real-time image of thetarget area to increase the visibility of the objects during relativelylow visible light level conditions without having to refocus ones eyesto monitor an indication device within the vehicle 10. Indicator 90 mayprovide some indication as to the operability of the system such asconfirming receipt of a signal such as a calibration signal or othercommands, warnings, and controls. Indicator 90 may also alert thevehicle operator with respect to tire pressure data, a safety event, ora comfort or convenience event.

Referring now also to FIG. 3, a schematic view of an advanced tiremonitoring system (ATMS) sensor 20 in accordance with an embodiment ofthe present invention is shown. The ATMS sensor 20 is illustratedmounted to a rim of a vehicle wheel 12 inside the tire. The sensor has atransmitter/receiver or transceiver 83. The transmitter/receiver. 83 iscoupled to antenna 19 for transmitting information to transceiver 80.The transmitter/receiver 83 may be used to receive an activation signalfrom an initiator 23 located at each wheel, if an initiator is used inthe particular application. The sensor circuit 20 may have variousinformation such as a serial number memory 04, a pressure sensor 85 fordetermining the pressure within the tire, a temperature sensor 86 fordetermining the temperature within the tire, and a motion detector inthe form of a multi-axis accelerometer 87. Preferably, the accelerometer87 is a MEMS device. The accelerometer may be used to activate theadvanced sensing system. The initial message is referred to as a “wake”message, meaning the sensor sensing circuit is now activated to send itspressure transmissions and the other data.

Each of the transceiver 83, memory 84, pressure sensor 85, temperaturesensor 86, and motion sensor 87 are coupled to a power source such asa-battery 88. The battery 88 may be a long-life battery capable oflasting the life of the tires. In another aspect, the battery may beomitted, or have a substantially smaller capacity. An energy schemeusing an RF field generated by an antenna on the vehicle, such asantenna 181, can be used to power the sensor circuit 20. This isgenerally indicated in FIG. 3 by the RF signal path in both sensorcircuit 20 and transceiver circuit 80. A self-generating energy schememay also be used wherein the device 20 scavenges energy from therotational movement of the tires. Such schemes may permit continuoussensor data transmission and/or longer sensor life when equipped with abattery supply.

A sensor function monitor 89 in the form of a microcontroller core orstate machine, for example, may also be incorporated into ATMS sensor 20circuit. The sensor function monitor 89 generates an error signal whenvarious portions of the ATMS circuit are not operating or are operatingincorrectly. Also, sensor function monitor may generate a signalindicating that the circuit is operating normally. The ATMS functionmonitor microcontroller 89 can locally pre-process the sensor datastreams prior to wireless delivery to the vehicle transceiver. It alsoprovides a supervisory function to control the overall operation of thesensor including processing, diagnostics and error detection.

The transceiver 80 in communication with the ATMS sensor 20, similarlyincludes a power source, transmitter/receiver device, microcontrollerand antenna. It also includes an interface for the vehiclecommunications bus (CAN bus). Thus, each ATMS sensor 20 communicateswirelessly with the controller 18 for at least a portion of itscommunication path. The transceiver 80 receives either the raw sensordata or the pre-processed sensor data from the tire sensors andcommunicates with the ATMS 18 for further processing with definedalgorithms.

An advantage of the ATMS sensors 20 just described is that it providestemperature and pressure data for each tire, as well as x, y and zacceleration data for each tire. This acceleration data is generatedmuch more directly than vehicle acceleration data generated byconventional IMU sensing systems. Traditional IMU systems determineroll, pitch and yaw above the vehicle suspension. Thus, signalpropagation is delayed and/or modified with other stimuli and transferfunctions because of the distance of the signal source, i.e., what isoccurring at the contact patches of the tires or to the tiresthemselves. The ATMS sensors 20 of the present invention reduce thesignal propagation path and latency because they are distributed veryclose to the road surface and other inputs, such as objects impactingthe tires. The ATMS sensors 20 allow data signals directly from therelevant tire/wheel. Items such as road surface characteristics, impactsand/or obstacles, tire defects, wheel defects and suspension defects canall be monitored by signature analysis of the wheel data provided by theATMS sensors 20.

Referring to FIG. 4, a block diagrammatic view of a convenience controlsystem 25 in accordance with an embodiment of the present invention isshown. The convenience control system 25 may consist of a rolloverstability controller RSC 56, as shown. It can also be a stand-alonesystem receiving input from only the ATMS sensors 20 and a limitednumber of other sensors. In this example, however, the conveniencecontrol system monitors many sensor inputs, including inputs from ATMSsensors 20 located at each wheel/tire of the vehicle. Front right (FR)and front left (FL) wheel/tires 12 a and 12 b and rear right (RR)wheel/tires 12 c and rear left (RL) wheel/tires 12 d, respectively, areshown and may be part of a vehicle, such as the vehicle 10. The vehiclemay also have a number of different types of front steering systems andrear steering systems, including having each of the front and rearwheels configured with a respective controllable actuator, the front andrear wheels having a conventional type system in which both of the frontwheels are controlled together and both of the rear wheels arecontrolled together, or a system having conventional front steering andindependently controllable rear steering for each of the wheels or viceversa.

The convenience control system 25 includes the controller or integratedsensing system (ISS) 26, which signals the safety device 51, thesuspension control 49, the engine/transmission controller 123 and thebrake controller 60 in response to information received from the ATMS18, and the sensor cluster 50. In other application, as described below,the ISS 26 may only indicate to the vehicle operator a sensed condition,without taking any other active measures to alter the sensed condition.

The controller 26 as well as the suspension control 49, the brakecontroller 60, and the engine/transmission controller 123 may bemicroprocessor based such as a computer having a central processingunit, memory (RAM and/or ROM), and associated input and output buses.The controllers 26, 49, 60, and 123 may be application-specificintegrated circuits or may be formed of other logic devices known in theart. The controllers 26, 49, 60, and 123 may each be a portion of acentral vehicle main control unit, an interactive vehicle dynamicsmodule, a restraints control module, a main safety controller, a controlcircuit having a power supply, combined into a single integratedcontroller, or may be a stand-alone controller as shown. The controllers26, 49, 60, and 123 may be configured to be mounted and located within avehicle dashboard or vehicle panel or in some other location on thevehicle 10.

The controllers and devices in communication with the ISS 26 aredescribed below. Thereafter, the inputs to the ISS 26 are described.

Referring to FIG. 4, a passive safety system may be in communicationwith the controller or ISS 26. The passive safety system 27 includescollision detection sensors 29, object detection sensors 28, and passivecountermeasures 30. The object detection sensors 28 monitor theenvironment around the vehicle 10 and generate object detection signalsupon detection of an object. The object detection sensors 28 may beinfrared, visible, ultrasonic, radar, active electro-magneticwave-ranging, or lidar based, a charged-coupled device, a series ofphotodiodes, or in some other form known in the art. Wave-rangingdevices may include radar, lidar, stereo camera pairs, 3-D imagers, withactive infrared illumination, or other wave-ranging devices known in theart. Vision sensors may refer to robotic cameras or other visual imagingcameras. The wave-ranging sensors and the vision sensors may bemonocular or binocular and may be used to obtain height, width, depth,range, range rate, angle, and any other visual aspect information.Monocular cameras may be used to obtain less accurate and less reliablerange and range rate data as compared to binocular cameras. The objectdetection sensors 28 may also be in the form of an object indicator. Theobject detection sensors 28 may be in various locations on the vehicleand any number of each may be utilized. The object detection sensors mayalso include occupant classification sensors (not shown). With respectto tripped rollover events, object detection sensors 28 detect objectswhich may cause a tripped rollover.

The collision detection sensors 29 are used to detect a collision andmore particularly, a side collision. The collision detection sensors 29may also be located anywhere on the vehicle 10 and generate collisiondetection signals in response to a collision. The collision detectionsensors 29 may include sensors that are used as vehicle status sensors,such as the yaw rate sensor 35, the lateral acceleration sensor 39, andthe longitudinal acceleration sensor 40. The collision detection sensors29 may also be in the form of an accelerometer, a piezoelectric sensor,a piezo-resistive sensor, a pressure sensor, a contact sensor, a straingage, or may be in some other form known in the art.

The passive countermeasures 30 may include internal air bag control,seatbelt control, knee bolster control, head restraint control, loadlimiting pedal control, load limiting steering control, seatbeltpretensioner control, external air bag control, pedestrian protectioncontrol, and other passive countermeasures known in the art. Air bagcontrol may include control over front, side, curtain, hood, dash, orother type of airbags known in the art. Pedestrian protection mayinclude a deployable vehicle hood, a bumper system, or other pedestrianprotective devices.

The brake control system 31 can also be in communication with the ISScontroller 26. The brake control system 31 includes the brake controller60 that actuates front vehicle brakes 62 a and 62 b and rear vehiclebrakes 62 c and 62 d. The vehicle brakes 62 are associated with thewheels 12 a-12 d. The brakes 62 may be independently actuatable throughthe brake controller 60. The brake controller 60 may control thehydraulic system of the vehicle 10. Of course, electrically actuatablebrakes may be used in the present invention. The brake controller 60 mayalso be in communication with other safety systems such as an antilockbrake system 64, a yaw stability control system 66 and a tractioncontrol system 68.

The steering control system 32, which may also communicate with the ISScontroller 26, can include a number of different types of front and rearsteering systems including having each of the front and rear wheels 12a-12 d configured with respective controllable adjusting elements 55A-D.The wheels 12 may be controlled together or individually. The ISScontroller 26 may control the position of the front right wheeladjusting element 55A, the front left wheel adjusting element 55B, therear left wheel adjusting element 55D, and the right rear wheeladjusting element 55C. Although as described above, two or more of theadjusting elements may be simultaneously controlled. For example, in arack-and-pinion system, the two wheels coupled thereto aresimultaneously controlled. Based on the inputs from sensors 35-47 andfrom the ATMS 18, the ISS controller 26 controls the steering positionand/or braking of the wheels. Thus, with respect to the steering controlsystem 32, the adjusting elements 55 permit directional control of theparticular wheel.

The controller 26 may also communicate with the suspension controlsystem 33. The suspension control system 33 includes the suspensioncontrol 49, the suspension 48, and the suspension adjusting elements55A-55D (FR_(SP), FL_(SP), RR_(SP), RL_(SP)) that are associated witheach wheel 12. The suspension control 49 and adjusting elements 55A-55Dmay be used to adjust the suspension 48 to prevent rollover. Theadjusting elements 55A-55D may include electrically, mechanically,pneumatically, and/or hydraulically operated actuators, adjustabledampers, or other known adjustment devices, and are described below inthe form of actuators. The adjusting elements 55 may allow for activemodification of the suspension response or geometry. For example, theymay comprise active dampers. The adjusting elements 55 may also bebushings which can electronically decouple the sway bar associated witha wheel to enhance suspension articulation. Another example is a bushingcomprising magnetorheological fluid and oil allowing it to articulatewithin the wheel joint to alter suspension geometry and/or the wheel'sNVH characteristics. In a further example, the suspension components 55may be pneumatic cylinders. The suspension control system 33 may alsooperate to adjust the tire pressure with central tire inflationcapability. For instance, the tire pressure may be lowered to traversesofter road conditions. This feature can be used in response to a roadsurface characteristic detection as described below, or a low tirepressure signal.

The controller 26 may also be in communication with the drivetraincontrol system 34. The drivetrain control system 34 includes an internalcombustion engine 120 or other engine known in the art. The engine 120may have a throttle device 142 coupled thereto, which is actuated by afoot pedal 144. The throttle device 142 may be part of a drive-by-wiresystem or by a direct mechanical linkage between the pedal 144 and thethrottle device 142. The engine controller 123 may be an independentcontroller or part of the controller 26. The engine controller 123 maybe used to reduce or increase the engine power. While a conventionalinternal combustion engine is contemplated, the vehicle 10 could also bepowered by a diesel engine or an electric engine or the vehicle could bea hybrid vehicle utilizing two or more types of power systems.

The drivetrain system 34 also includes a transmission 122, which iscoupled to the engine 120. The transmission 122 may be an automatictransmission or a manual transmission. A gear selector 150 is used toselect the various gears of the transmission 122. The gear selector 150may be a shift lever used to select park, reverse, neutral, and drivepositions of an automatic transmission. Of course, in the case ofelectric vehicles, electric motors may replace the conventionalengine/transmission setup shown in this example.

Safety device 51 may control one or more passive safety countermeasuressuch as airbags 30 or a steering actuator 55A-D at one or more of thewheels 12 a, 12 b, 12 c, 12 d of the vehicle. The safety device 51 mayalso operate the suspension control/tire inflator 49 as described above.

A lateral support system 70 may also be in communication with theconvenience controller 26, either directly or through the safety device51. The lateral support system 70 is adapted to mitigate trippedrollover events. It can include a deployable set of linkages and one ormore arms, which each have a wheel set attached to the outwardlyextending end thereof. The inward end of the arm is attached to adeploying mechanism. In normal driving conditions the wheels sets arenot in contact with the driving surface. The lateral support system 70may also or alternatively include laterally deployable airbags. Theairbags are also outwardly deployed to prevent or mitigate a trippedrollover. The airbags may be deployed from any location on the vehicle10 and any number of airbags may be utilized.

Indicator 90 may also be in communication with the conveniencecontroller 26 directly, or indirectly though the safety device 51. Itmay be used to indicate to a vehicle operator various vehicle-relatedand status information.

In this example, the controller 26 receives numerous inputs to aide indetermining vehicle dynamic conditions. For example, it may determinewhether a rollover event is in progress or is imminent. The controller26 may include a signal multiplexer 50 that receives the signals fromthe sensors 20 and 35-47. In this example, the signal multiplexer 50provides the signals to a roll stability control (RSC) feedback controlcommand 56 which is part of the convenience controller 25. As mentionedabove, however, the convenience system could be implemented with manyfewer sensor inputs and, indeed, may only receive input from ATMSsensors 20 to determine the roadway surface conditions and otherconvenience functions described below.

The controller 26 takes advantage of the information provided by theadvanced tire monitoring sensors 20 described above, as well as thetraditional vehicle dynamics sensors 35-47 in monitoring for potentialrollover events and other vehicle and roadway dynamics. Thus, theacceleration data, temperature data and pressure data for each wheel isanalyzed in various safety schemes described in further detail withrespect to FIGS. 5 through 10. Heretofore, control systems have notconsidered coordinate acceleration data at each wheel. Rather, suchvehicle and roadway data was only determined by means such asconventional IMU units, typically with reference to the body centerframe, and located above the suspension line of the vehicle.

Briefly, the vehicle status sensors 35-47 may include the yaw ratesensor 35, the pitch rate sensor 36, the roll rate sensor 37, thevertical acceleration sensor 38, lateral acceleration sensor 39,longitudinal acceleration sensor 40, the speed sensor 41, the steeringwheel angle velocity sensor 42, the steering angle (of the wheels oractuator) position sensor 43, the suspension load sensor 44, thesuspension position sensor 45, the accelerator/throttle signal generator46, and the brake pedal/brake signal generator 47. It should be notedthat various combinations and sub-combinations of the sensors may beused. The steering wheel angle sensor 42, the accelerator/throttlesignal generator 46, and the brake pedal/brake signal generator 47 areconsidered driver input sensors, since they are associated with a pedal,a wheel, or some other driver input device. Depending on the desiredsensitivity of the system and various other factors, not all the sensors35-47 may be used in a commercial embodiment. These sensors may be usedin a conventional rollover stability control scheme, if the vehicle isso equipped, as in this example. One example of a rollover stabilitycontrol scheme using such sensors, as well as an advanced tiremonitoring system is disclosed in U.S. patent application Ser. No.11/639,131, which is incorporated by reference herein. In the comfortand convenience schemes discussed below, however, the control method isbased on feedback from the ATMS 18 alone, or in combination with onlyone or a few other sensor inputs such as the driver input and vehiclespeed. Thus, the remaining sensors 35-47 are only included forcompleteness, and may only act as confirmatory sensors to the detectedcondition based on the ATMS 18 data.

The vehicle dynamic sensors 35-40 may be located at the center ofgravity of the vehicle 10. Those skilled in the art will recognize thatthe sensors may also be located off the center of gravity and translatedequivalently thereto.

FIG. 5 is a logic flow diagram illustrating a method of operating acontrol system of a vehicle in accordance with an embodiment of thepresent invention providing roadway surface condition estimation.Although the following steps are described primarily with respect to theembodiments of FIGS. 1-4, they may be modified and applied to otherembodiments of the present invention, including vehicle embodimentswherein less than all sensors 35-47 are included. Indeed, in thisexample, only an ATMS sensor 20 at each wheel and vehicle speed data areanalyzed.

In general terms, the roadway surface condition estimation schemedetects the type of road surface being traversed by the vehicle, andactively adjusts vehicle sub-systems accordingly to improve the ridecomfort and/or vehicle handling. Roadway surfaces are differentiated byan analysis of the tire acceleration signals provided by the ATMS sensor20 at each wheel. Rough road surfaces such as dirt roads exhibit higheracceleration signal and spectral content, i.e., acceleration frequencycomponents, in the X and Z axis as compared to smooth road surfaces suchas asphalt roads. On this basis, roadway surfaces can be detected, andsuspension and/or tire adjustments can be made to improve vehicle rideand handling. Other road surface conditions can also be discerned suchas ice, water, gravel, snow, etc.

Referring to FIG. 5, in step 200, tire signals are generated, which areindicative of the current tire pressure, temperature and multi-axisaccelerations within each tire of the vehicle. This information isprovided by the advanced tire monitoring system sensors 20. Steps 202,204 and 206 preprocess the data generated by the ATMS sensors 20. In theblock 202 the data is segmented and parsed into discrete time windowsand transformed from the time domain into the frequency domain using theFourier Transform (FT) techniques. Alternate embodiments may use otherfrequency transformation techniques such as wavelet transformationtechniques to transform the time domain data into its frequency domainrepresentation. In block 206 the signal amplitude-time data is parsedinto discrete time windows and signal amplitude vs. time table isgenerated for each time window for each of the sensor data as shown inFIG. 6. The generated tables are used in the subsequent algorithm blocksand are compared to known stored road surface conditions tables todetermine the current road surface conditions. In block 204 a signalmagnitude vs. frequency table is generated for each time window as shownin FIG. 7. The generated tables are used in the subsequent algorithmblocks and are compared to known stored road surface conditions tablesto determine the current road surface conditions. As mentioned above,because the data is generated inside each tire for the vehicle, thesignature profiles of the sensor data provide direct insight into whateach tire is experiencing while it contacts the road surface. This datais generated much more directly than vehicle acceleration data generatedby conventional IMU sensing systems because traditional IMU systemsdetermine roll, pitch and yaw and coordinate accelerations above thevehicle suspension. The ATMS sensors 20 eliminate signal propagationthrough the suspension, and provide a clearer “view” of the vehicledynamics.

The preprocessed ATMS sensor data is then analyzed according to roadwaysurface condition estimation criteria in step 208. A more detailedexplanation of the roadway surface condition estimation criteria isprovided in the example of FIG. 8. In this example, the ATMS sensorsignals are compared to stored sensor frequency response signatures andstored amplitude/time response signatures from block 210.

The robustness of the system can be improved further by combining awheel slip analysis with the ATMS data analysis. For example, thelongitudinal wheel slip of a given wheel can be determined according to:S=(wr/v)−1  (1)wherein w is the wheel's angular velocity, r is the radius of the tire,and v is the linear wheel/tire velocity. This slip value can then becompared to sensed ATMS data to confirm the roadway surface conditionestimation.

The determined roadway surface condition estimation is then broadcast toother vehicle subsystems. This may include safety modules such as theactive/passive safety systems, ABS, RSC, or integrated vehicle dynamicscontroller. By broadcasting the roadway surface conditions, these othersystems can then optimize their performance based upon the sensedroadway surface. For instance, if a rollover event is declared, but theroadway surface conditions are not optimal (for example, slipperyconditions), the thresholds that are used in activating or initiatinginterventions may be adjusted, scaled, opened, or relaxed, to alterintervention timing. In such situations, earlier interventions may bedesired. In another example of broadcasting, a pre-arm signal forsafety-related countermeasures based upon the ATMS data may begenerated. Pre-arming would be appropriate for the roll stabilitycontrol system as well as the restraints control system. The brakepressure applied during any intervention or countermeasure may also bemodified as a result of the roadway surface estimation. For instance,the brake pressure may be tiered based on the contact patch conditionsat each tire: full range or maximum brake pressure range, a reducedrange or brake pressure limiting range, and an inactive range or brakepressure prevented range. When the contact patch surface roughness isestimated to be high or greater than or equal to a first surfaceroughness threshold value, the control system may apply a brake pressureup to a maximum threshold. In those cases, the full range brake controlfunctions are maintained. When the surface roughness estimate of a tireof concern is in the reduced range or between a first roadway surfaceroughness threshold TPT1 and a second roadway surface roughnessthreshold TPT2, the control system may apply a reduced or limited brakepressure, which is less than that which would normally be applied. Inthe reduced range the amount that the brake pressure is limited isgradually or progressively increased. This increase may be linear, maybe non-linear, or may result using some other relationship. When theroadway surface roughness estimate of a tire of concern is less than orequal to the second threshold TPT2, the control system is prevented fromapplying brake pressure. Although the control system is prevented fromapplying a brake pressure, brake pressure may be applied manually by avehicle operator. In another embodiment, the control system can overridethe manual brakes and limits or prevents manual brake pressure.

Optionally, in step 213, the tire pressure may be changed in response tothe detected roadway surface condition and/or merely on a low or hightire pressure indication. This may be accomplished by the central tireinflation device 49 (FIG. 4), if the vehicle is so equipped. Thus, ifthe tires are at a lower than normal pressure, and the roadway surfaceis hard, the tire should be inflated to reduce the potential for tirede-beading, de-treading, or other tire damage associated with lowpressure driving. Similarly, the tires may be maintained or put in a lowpressure state to improve soft road condition handling (sand, loosegravel). When the vehicle encounters a hard surface for sufficientlength of time, the ATMS 18 would indicate the roadway surfacecondition, and the tires could be inflated to a more appropriatepressure.

In step 214, the control system may also indicate via an indicator, suchas the indicator 90 (FIG. 4), to a vehicle operator the roadway surfacecondition and/or the status of each tire. The control system mayindicate that a tire pressure is low and the extent thereof. Thisinformation may also be stored, viewed, and downloaded for future reviewand/or evaluation. The viewing and downloading may be to an offboard oroffsite system. The control system may also indicate to a vehicleoperator that active tasks are being performed and the status of thevehicle. This indicated information may also be stored, viewed, anddownloaded for future review and/or evaluation. The viewing anddownloading may be to an offboard or offsite system.

The above tasks may be performed via any one or more of the hereinmentioned controllers, control systems, stability control systems, orthe like.

The above-described steps are meant to be illustrative examples; thesteps may be performed sequentially, synchronously, simultaneously, orin a different order depending upon the application.

Referring now to FIG. 8, a logic flow diagram illustrating oneparticular method of ATMS sensor-based roadway surface conditionestimation in accordance with an embodiment of the present invention isshown. This process is one example of the roadway surface conditionestimation as called for in step 208 of FIG. 5. Of course, this examplemay be modified and applied to other embodiments of the presentinvention.

The routine starts at steps 216 and 218 by determining whether thevehicle; is moving or braking. If the vehicle is moving, but notbraking, the logic continues. Otherwise, no roadway surface condition isestimated in step 220.

The sensed tire data from steps 202, 204 and 206 as described above, isthen compared to stored values from information block 210 in step 222.The stored Fourier response may comprise a lookup table of sensorsignatures, each indicative of a roadway surface condition at variousspeeds. If the current frequency response characteristic matches anystored frequency response characteristic at the same vehicle speedindicative of a particular roadway surface condition in step 224, thelogic continues to step 226. Otherwise, no roadway surface condition isestimated in step 220.

If a roadway surface condition match exists for the sensed ATMS data,step 226 begins the process of determining which roadway surface hasbeen estimated. This continues through N stored roadway surfacesignatures, as shown in step 228. If the first tested roadway surfacecondition matches the sensed data, it is broadcast to the other vehiclesubsystems in step 230, as described above. The confidence level of theroadway surface condition estimation can be determined from thecloseness of the match and/or by confirmatory calculations of wheel slipas discussed above. Further, if the system has a high confidence levelregarding the declared roadway surface condition in step 232, and it isdeemed useful driver information, it may be indicated to the vehicleoperator, as in step 214. Again, for each of N stored roadwayconditions, similar steps are indicated at 236, 238 and 240.

FIG. 9 is a logic flow diagram illustrating a method of operating acontrol system of a vehicle in accordance with an embodiment of thepresent invention providing active suspension control. Although thefollowing steps are described primarily with respect to the embodimentsof FIGS. 1-4, they may be modified and applied to other embodiments ofthe present invention, including vehicle embodiments wherein less thanall sensors 35-47 are included. Indeed, in this example, only ATMSsensor 20 data at each wheel and the vehicle speed data are analyzed.

In general terms, the active suspension scheme detects the type of roadsurface being traversed by the vehicle, and actively adjusts the vehiclesuspension to improve the ride comfort and/or vehicle handling. Roadwaysurfaces are differentiated by an analysis of the tire/wheelacceleration signals provided by the ATMS sensor 20 at each wheel, asdescribed above. Rough road surfaces such as dirt roads exhibit higheracceleration signal and spectral content, i.e., acceleration frequencycomponents, in the X and Z axis as compared to smooth road surfaces suchas asphalt roads. On this basis, roadway surfaces can be detected, andsuspension and/or tire adjustments can be made to improve vehicle rideand handling. Additionally, if the vehicle is equipped withoperator-selectable handling, the desired vehicle handling can beincorporated into the active suspension scheme.

Adjustments to the suspension contemplated include modifying suspensiondampers, ride height, and activating suspension bushings to modifysuspension geometry and characteristics at the wheels. Active suspensiondampers vary the amount of damping performance of the shock absorbers.They typically use megnetoreological fluids or pneumatic pressure toprovide an extremely responsive change to damping performance. Mostconventional suspension adjustment systems are “open loop” in that theyrely upon operator input to adjust the suspension. In the example of thepresent invention, besides allowing open loop control, the systempermits “closed loop” suspension control based on feedback from the ATMS18. Ride height can be modified by an active air suspension system whichuses compressed air to control suspension response and vehicle rideheight. Again, convention systems are largely open loop systems thatonly sense vehicle height, whereas the present system permits closedloop control with respect to ride height and roadway surface conditions.Other active suspension components include sway bars that can beelectronically decoupled by bushings to provide enhanced suspensionarticulation. Such features could also be used to automatically correctwheel misalignment, which could also be sensed by the ATMS 18.

Referring to FIG. 9, in step 300, ATMS signals are generated, which areindicative of the current tire pressure and temperature within andmulti-axis accelerations at each wheel/tire of the vehicle. Thisinformation is provided by the ATMS sensors 20. Steps 302, 304 and 306preprocess the data generated by the ATMS sensors 20. As mentionedabove, because the data is generated inside each tire for the vehicle,the signature profiles of the sensor data provide direct insight intowhat each tire is experiencing while it contacts the road surface. Thisdata is generated much more directly than vehicle acceleration datagenerated by conventional IMU sensing systems because traditional IMUsystems determine roll, pitch and yaw and coordinate accelerations abovethe vehicle suspension. The ATMS sensors 20 eliminate signal propagationthrough the suspension, and provide a clearer “view” of the vehicledynamics.

The preprocessed ATMS sensor data is then analyzed according to activesuspension control criteria in step 308. A more detailed explanation ofthe active suspension control is provided in the example of FIG. 10. Inthis example, the sensor signals are compared to stored sensor frequencyresponse signatures from block 310 and stored amplitude/time responsesignatures from block 309.

If the vehicle operator has selected a desired driving characteristicfor the vehicle, by way of a user selectable input, this could also beprovided from block 311. Such indicators may include “sport”, “normal”or “comfort” handling and ride characteristics for the vehicle.

In step 312, the user-selected input 311 and active suspension controlscheme 308 are used to actively tune the suspension to provide improvedride and handling. In one example, the vehicle is operated according tothe user-selected ride setting, but actively adjusted based on thesensed road conditions. For instance, if the user selected a “sport” or“firm” ride characteristic, the perceived stiffness of the suspensionwould be softened upon detection of a rough road surface to alleviateany undesirable operator feedback or noise, vibration and Harshness.

The above-described steps are meant to be illustrative examples; thesteps may be performed sequentially, synchronously, simultaneously, orin a different order depending upon the application.

Referring now to FIG. 10, a logic flow diagram illustrating oneparticular method of ATMS sensor-based active suspension control inaccordance with an embodiment of the present invention is shown. Thisprocess is one example of the active suspension control as called for instep 308 of FIG. 9. Of course, this example may be modified and appliedto other embodiments of the present invention.

The routine starts at steps 316 and 318 by determining whether thevehicle is moving or braking. If the vehicle is moving, but not braking,the logic continues. Otherwise, no suspension characteristics aremodified in step 320.

The sensed tire data from steps 302 and 304 as described above, is thencompared to stored values at the same vehicle speed from informationblock 310 in step 322. The stored Fourier response may comprise a lookuptable of sensor signatures, each indicative of a roadway surfacecondition. If the current frequency response characteristic iscompatible with the operator-input suspension mode in step 324, nosuspension adjustment is made. Otherwise, if the selected suspensionmode is incompatible or undesirable for the detected road condition(i.e., “firm” ride on a rough road), the suspension is adjustedaccordingly in step 326. The user-selected suspension mode is determinedfrom block 311.

In step 328, the detected acceleration data, including theamplitude/time response characteristics of the ATMS data from block 306is compared to stored amplitude/time response signatures at the samevehicle speed from block 309. The user-selected ride mode from block 311is also considered in block 330. If the roadway surface condition-basedsuspension response matches the user-selected suspension mode, nochanges are made. Otherwise, the suspension is adapted in step 326 as afunction of the determined suspension setting according to the detectedroad surface conditions, taking into account the user-selected setting.As mentioned above, suspension adjustments can include modifyingsuspension dampers; ride height, and activating suspension bushings tomodify suspension geometry and characteristics at the wheels. Further,any actions with regard to the suspension may be indicated to thevehicle operator, as before.

Thus, the suspension control system adjusts the vehicle suspensioncharacteristics according to the user-selected suspension value when theuser-selected value and the detected road surface conditions are thecompatible; and adjusts the vehicle suspension characteristics accordingto the detected road surface condition when the user-selected suspensionvalue and detected road surface conditions are incompatible, such as asports ride selection under estimated rough road conditions.

In another aspect of active suspension control, rear wheel hopmitigation may be included. Rear wheel hop occurs when one or typically,both rear wheels vertically and laterally jump from uneven roadsurfaces. Such occurrences are common on dirt roads and as a result oftar strips in concrete. Rear wheel hop can cause sudden lateral(sideways) rear vehicle movement leading to temporary vehicleinstability or compromised control.

Rear wheel hop mitigation may be implemented as part of the activesuspension control. During a rear wheel hop event, the rear wheel'sexperience both a Z (vertical) and Y (lateral) acceleration which can bereadily detected by the ATMS 18. These signals will only be detected inthe rear wheels with the exception of some Z axis acceleration componentfrom the road surface. Thus, wheel signature profiles indicative of rearwheel hop can be stored as in blocks 309 and 310 and compared to thesensed wheel data from blocks 302, 304 and 306.

In response to a detected rear wheel hop event, step 326 can implementcountermeasures to mitigate or prevent further wheel hop. Suchcountermeasures can include suspension adjustments, as mentioned above.Alternatively, or additionally, they may include reducing the enginepower and/or braking the associated wheels.

While particular embodiments of the invention have been shown anddescribed, numerous variations and alternate embodiments will occur tothose skilled in the art. Accordingly, it is intended that the inventionbe limited only in terms of the appended claims.

1. A system for a vehicle comprising: a tire sensor located within atleast one wheel of the vehicle and generating a tire signal comprisingpressure, temperature and multi-axis acceleration data; at least onevehicle dynamics sensor providing a vehicle dynamics signal; acontroller in communication with the tire sensor and the at least onevehicle dynamics signal, the controller generating a first suspensionvalue in response to the vehicle dynamics signal and as a function ofthe multi-axis acceleration data of the tire signal; a suspensioncontrol system receiving the first suspension value from the controllerand adjusting vehicle suspension characteristics in response to thefirst suspension value.
 2. A system according to claim 1 furthercomprising a user-selected second suspension value, and wherein thesuspension control system adjusts the vehicle suspension characteristicsas a function of the first and second suspension values.
 3. A systemaccording to claim 2 wherein the controller generates a roadway surfacecondition estimation value as a function of the multi-axis accelerationdata from the tire signal, and modifies the first suspension value as afunction of the roadway surface condition estimation value.
 4. A systemaccording to claim 1 wherein the controller generates the firstsuspension value as a function of the tire signal by comparing frequencyand amplitude response characteristics of the tire signal to storedfrequency and amplitude response characteristics indicative of differentroadway surfaces.
 5. A system for a vehicle comprising: a tire sensorlocated within at least one wheel of the vehicle and generating a tiresignal comprising pressure, temperature and multi-axis accelerationdata; at least one vehicle dynamics sensor providing a vehicle dynamicssignal; a controller in communication with the tire sensor and the atleast one vehicle dynamics signal, the controller generating a firstsuspension value in response to the vehicle dynamics signal and as afunction of the multi-axis acceleration data of the tire signal; asuspension control system for receiving the first suspension value fromthe controller and adjusting vehicle suspension characteristics inresponse to the first suspension value; a user-selected secondsuspension value, the suspension control system adjusts the vehiclesuspension characteristics according to the second suspension value whenthe first and second suspension values are compatible, and adjusts thevehicle suspension characteristics according to the first suspensionvalue when the first and second suspension values are incompatible.
 6. Asystem for a vehicle comprising: a tire sensor located within each wheelof the vehicle and generating a tire signal comprising pressure,temperature and multi-axis acceleration data; at least one vehicledynamics sensor providing a vehicle dynamics signal; a controllercommunicating with the tire sensor and the at least one vehicle dynamicssensor, the controller generating a first suspension value in responseto the vehicle dynamics signal and as a function of the multi-axisacceleration data of the tire signal; and a suspension control systemreceiving the first suspension value from the controller and adjustingvehicle suspension characteristics in response to the first suspensionvalue.
 7. A system according to claim 6 further comprising auser-selected second suspension value, and wherein the suspensioncontrol system adjusts the vehicle suspension characteristics as afunction of the first and second suspension values.
 8. A systemaccording to claim 7 wherein the controller generates a roadway surfacecondition estimation value as a function of the multi-axis accelerationdata from the tire signal, and modifies the first suspension value as afunction of the roadway surface condition estimation value.
 9. A systemaccording to claim 6 wherein the controller generates the firstsuspension value as a function of the tire signal by comparing frequencyand amplitude response characteristics of the tire signal to storedfrequency and amplitude response characteristics indicative of differentroadway surfaces.
 10. A system for a vehicle comprising: a tire sensorlocated within each wheel of the vehicle and generating a tire signalcomprising pressure, temperature and multi-axis acceleration data; atleast one vehicle dynamics sensor providing a vehicle dynamics signal; acontroller communicating with the tire sensor and the at least onevehicle dynamics sensor, the controller generating a first suspensionvalue in response to the vehicle dynamics signal and as a function ofthe multi-axis acceleration data of the tire signal; a user-selectedsecond suspension value; a suspension control system receiving the firstsuspension values from the controller, the suspension control systemadjusts the vehicle suspension characteristics according to the secondsuspension value when the first and second suspension values arecompatible, and adjusts the vehicle suspension characteristics accordingto the first suspension value when the first and second suspensionvalues are incompatible.